The present invention relates to a spacer spraying device for spraying a powdery spacer and, more particularly, to a spacer spraying device for spraying a powdery spacer onto a substrate to be included in an LCD (Liquid Crystal Display) in order to form a preselected gap between it and the other substrate.
It is a common practice with an LCD to form a spacer between a pair of substrates for spacing them from each other. The spacer is implemented by acrylic resin powder and deposited on the top of a substrate by either one of a wet process and a dry process. In the wet process, a preselected amount of spacer is mixed with, e.g., water or alcohol solvent and then sprayed into a spray chamber in which a substrate is positioned. At the same time, the inside of the spray chamber is heated. As a result, water or solvent is evaporated while only the spacer is deposited on the top of the substrate. A problem with the wet process is that when water or solvent is not fully evaporated, it leaves marks on the top of the substrate which would form undesirable spots on the resulting LCD or bring about irregular display. Another problem is that the spacers formed on two substrates each coheres in the form of masses and renders the gap between the substrates adhered to each other inadequate.
The dry process uses a gas, as follows. A preselected amount of spacer is fed to a nozzle via a metal pipe and a resin pipe together with air compressed to 2 kg/cm.sup.2 to 3 kg/cm.sup.2. The nozzle sprays the spacer into a spray chamber in which a substrate is positioned, while being moved zigzag by a drive motor. A first problem with the dry process is that the atomized spacer in the chamber deposits on the inner side walls and top wall of the chamber and is apt to drop in the form of masses due to, e.g., vibration ascribable to the movement of the nozzle. The deposition of the spacer on the above walls is ascribable to convection in the chamber, as will be described specifically later. A second problem is the waste of spacer ascribable to the fact that the amount of spacer for a single substrate should take account of the part of the spacer to deposit on the walls of the chamber, the spacer sequentially deposits on the walls until the walls reach the same potential as the spacer.
Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 5-127169, 6-3679, 6-34982, and 6-148586.